Alkali metal bicarbonate is a commodity reagent which has found application in a broad variety of products such as laundry detergents, deodorizers, creams and lotions, dentifrices, antacids, buffers, fungicides, fire extinguishers, and the like.
Alkali metal bicarbonate powder normally does not have a free-flowing capability, which is a disadvantage for purposes of storing and dispensing in bulk quantities.
Commercial scale manufacturing processes produce an alkali metal bicarbonate product which contains a residual quantity of alkali metal carbonate, usually as a trace residue on the surfaces of the crystalline alkali metal bicarbonate particles. Alkali metal carbonate is hygroscopic, and its presence in alkali metal bicarbonate diminishes the free-flow properties of the bulk powder.
Also, when alkali metal bicarbonate is incorporated as a deodorant ingredient in personal care formulations such as cosmetic stick and roll-on antiperspirant products, the presence of an alkali metal carbonate impurity causes skin irritation because of its high pH alkalinity.
There is continuing interest in the availability of bulk alkali metal bicarbonate powder which is free-flowing and substantially free of residual alkali metal carbonate content.
Accordingly, it is an object of this invention to provide an alkali metal bicarbonate powder which is free-flowing and which is essentially free of alkali metal carbonate impurity.
It is another object of this invention to provide a process for reducing the alkali metal carbonate impurity content of bulk alkali metal bicarbonate powder.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.